Plasticizers are typically required in elastomeric formulations for improved processibility, and reduced brittleness in the final manufactured article. However, such plasticizers generally reduce the mechanical properties, and, due to migration, reduce the aging resistance, of cured elastomeric formulations. There is a need for new crosslinked elastomeric formulations containing low volatility polymers, instead of conventional plasticizers, and which have maintained processibility. These crosslinked formulations should also have excellent mechanical and aging properties.
U.S. Publication No. 2006/0030667 discloses a thermoplastic composition comprising (i) from 1 to 99 percent by weight of at least one thermoplastic copolymer, for example, a styrene block copolymer, and (ii) from 1 to 99 percent by weight of at least one homogeneously branched ethylene/α-olefin interpolymer, for example an ethylene/1-octene copolymer, having a density of less than, or equal to, 0.899 g/cc, and a Brookfield viscosity of greater than 500 cP (350° F.).
U.S. Publication No. 2009/0043049 discloses a polyolefin composition that contains 60 to 99 weight percent of one or more polyolefin polymers, and 1 to 40 weight percent of a regularly branched PAO (poly(alpha-olefin)), based on the total weight of the polyolefin polymer(s) and the regularly branched PAO. The PAO includes oligomers of one or more C2 to C20 alpha-olefins having a kinematic viscosity, at 100° C., of 3 to 3000 cSt, a Branching Irregularity Index (BII) of 0.40 or less, a molar-average carbon number of 6 to 14, and a Mw/Mn of less than 2.3.
U.S. Pat. No. 7,335,696 discloses highly filled polymer compositions comprising a low molecular weight ethylene and/or alpha olefin homopolymers and copolymers, or blends therefrom, filled with high concentrations of fillers or additives. See also U.S. Pat. No. 7,781,510.
Additional compositions are described in the following references: U.S. Pat. Nos. 7,531,601, 7,622,523, 7,619,026; U.S. Publication Nos. 2009/0043049, 2008/0227919; International Publication Nos. WO 2004/031250, WO 2004/087804, WO 2001/40374, and WO 1997/33921.
There remains a need for new elastomeric compositions, containing low volatility polymers that maintain the processibility of the compositions, and which, when cured, have excellent mechanical properties and excellent properties after aging. These needs and others have been met by the following invention.